1. Field of the Invention
The invention relates to an electrical beverage preparation machine for the preparation/dispensing of a beverage, and to a method of operating such a beverage preparation machine.
2. The Prior Art
Electrical beverage preparation machines, for example for preparing/dispensing coffee, espresso, steam, hot water, hot milk, foamed milk, etc. are part of the basic equipment of many households, restaurants, factories or offices. For practical reasons, such machines are usually operated so that they are constantly connected to a main power supply, generally by a plug, even when there is no need to prepare a beverage.
So that beverage preparation machines can be constantly connected to the main power supply, but operated in such a way that minimal energy consumption is guaranteed at the same time as maximum safety, such machines are generally fitted with a switch that can be operated by a user in order to switch the machine on or off as required, i.e. to switch the (electrical) power supplying the machine on or off, or, if necessary to reduce it to a predetermined minimum value.
To date, various designs for switches intended for use in beverage preparation machines have become known.
Conventional beverage preparation machines generally have an electric circuit, connectable to a main supply, to which a control unit and one or more functional units controlled by the control unit are connected, said functional units being intended for carrying out a process performable by the machine (e.g. grinding coffee, heating water, brewing coffee, generating steam, recording machine operating data, displaying operating data and/or the operating status of the machine etc).
In many beverage preparation machines of this type, the control unit is constantly supplied with power when the electric circuit is connected to the power supply. A switch is provided to switch the power required for operating the relevant functional units on and off. In this case, when the power supply to the relevant functional unit is switched off, the machine goes into standby mode. As the control unit is constantly being supplied with power, the control unit is always ready to carry out certain functions (for example, monitoring the switch or checking certain sensors provided to monitor the operation of the machine, or monitoring buttons or interfaces that can be influenced by users in order to operate the machine).
This design has the drawback that the beverage preparation machine is constantly using power. There is also a certain safety risk, as the components of the electrical systems constantly consuming power could cause harm or damage, for example as a result of faults occurring or dangerous actions by users. It is therefore disadvantageous to leave such a beverage preparation machine unsupervised for a longer period of time if it is connected to the main supply.
In contrast to the aforementioned design, other known beverage preparation machines have two switches in their electric circuit: a first switch (main switch) which when operated can switch on or off the power for all consumers connected to the electric circuit, i.e. both for the control unit and for the relevant functional units, and a second switch which exclusively switches the power required for the relevant functional units on and off.
The aforementioned design has the advantage that the power in the electric circuit can be completely switched off through appropriate operation of the relevant switch. On the other hand, there is the disadvantage of a user confusing the available switches and not using the relevant switch for its intended purpose. For example there is a risk that by operating the first switch, a user simultaneously switches off the power for the control unit and the functional unit at a time when one of the functional units is just carrying out one of the processes intended for preparing/dispensing a beverage. The current could be switched off at a time when the functional unit is in an operating mode in which switching off the power is problematical. For example, in the case of a functional unit comprising mechanical components that move when in operation and could become jammed in an undesirable position in the event of a power outage.